The distribution of wind-driven rain loads on building facades is of high importance in evaluating the hygrothermal performance and durability of building envelopes. Wind-driven rain is known to be a major source of moisture loads on building facades and is responsible for numerous cases of facade failure. One of the classical solutions for preventing the building envelope from being extensively exposed to such loads is the use of overhangs. In this work, the effects of different overhang lengths on the distribution of wind-driven rain on building facades are investigated by numerical methods. To check validity, the results are compared to existing data reported in the literature. Calculated values of catch ratio at two sample positions on the front facade of a simple cubic building are in good agreement with previously published results. The protective effect of overhangs is shown by calculating catch ratio values for cases where rectangular overhangs were added to the cubic building. Results suggest that the introduction of the overhang can significantly change both the amount and the pattern of the wind-driven rain wetting of the facade. This change may, in certain points, be unfavourable.
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